Hi Giri,
many thanks, I confirm that putting “undefined” (if the field is not previously empty) or not putting anything (if the field is already empty) the problems is solved.
Here some code to help
To recap: if you need to clear a refernce field already filled with data, write code as below.
$w( ’ # your-dataset ’ ).setFieldValue( ‘your-field’ , undefined);
in my case this code in under a “onclick()” action for a button connected to a dataset with “send” action